Other Employee Benefit Programs Defined Contribution Plans (Details)	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2015 CAD	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 9,532,000		$ 10,400,000	$ 9,460,000
G&W 401k savings plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.00%	4.00%
Canadian retirement benefit plan 1 [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%	6.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount	$ 3,017	CAD 3,500
Canadian retirement benefit plan 2 [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	5.00%	5.00%
Australian retirement benefit plan [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	9.50%	9.50%	9.50%	9.25%